Electrifying an HP StreetMachine

[xrpb11a]

Hi all,
I've been researching doing the above for the past month or so. Never electrified a bike before, but am pretty proficient with tools and such. I'd like some comments (funny and serious) on how you would configure this bike, versus what I have in mind at this point.

The bike:
HP Velotechnik StreetMachine GTE, SRAM DualDrive 24 speed ( 3 speed rear hub, 8 sprocket cassette ), front and rear suspension, 26" rear wheel, 20" front short wheel base recumbent, BSA 68mm bottom bracket.
http://www.hpvelotechnik.com/produkte/sm/gte/technik_e.html

The need:
All pleasure, I mostly ride bike paths and some street. Am at the base of sierra mountains so sometimes all flat, sometimes I have some hilly climbs...nothing very long but can get a little steep. Am looking to continue riding the bike like a bike, but have the option to maintain speed going up hills if I get lazy....sometimes engaging the motor on flats too just because I can! :lol:
No need to go real fast on this bike...20mph seems fine...I rented a pedalec which was limited to 15mph, and that was ok..not sure how safe a short wheel base recumbent would be at 25-30mph and don't want to be the guinea pig.

Started here:
Looked at hub motors. For my needs ruled out direct drives ( too heavy, big, adds to pedal resistance when disengaged ).
Looked at 250-500 watt geared rear hub motors...ruled out front hub due to Spinner Grind2 shocks, aluminum alloy dropouts, and short wheel base should something break and I go flying...
Rear wheel hub motor would mean I'd lose the rear hub sram dualdrive internal 3 speed, drop down to a 7 speed freewheel, and have to add two more chainrings to the current front single chainring ( I think 40 teeth ) along with the shifting stuff. Same dropout problems but probably minimized with torque arms ( although I don't like the idea of tightening the hose clamps on the torque arms and damaging the paintjob/metal )

Wound up here:
Started researching mid drives, since they would let me keep the current gear setup ( I think...SRAM internal 3 speed hub up to the task of a middrive?? ). Although they are not as stealthy, I could get good torque using the gears to minimize motor burnout and use intelligent gear shifting to eliminate chain wreck...
Currently looking at 350-500 watt BBS01 / BBS02...

This place:
Has got so much info, and I have absorbed and read so much in the past month that now I am on information overload and frozen in my tracks in the decision making process

Any and all comments welcome. I need some objective 3rd party viewpoints to regain focus!!
How would you go about electrifying this bike??

 

[Triketech]

Good to see a fellow HPV fan.

I've been exploring various drives and how to match them to user needs; "Choosing a Power Assist System".

IMO, the trade-offs between DD and geared drives differ with wheel size; at 26" on the SM, the geared drive offers a better option regarding hub motors.

My favorite is the MAC 10T which adds about 9 lbs over the DD3 hub you have, and add another 1.5 Lbs for the controller. The trouble is you would have only 8 gears unless you update the gear system.

Nice thing with the HPV is they use 60mm frame tubing which makes the boom stout enough for a mid-drive.

There is a fellow in Canada using a DD3 on an ICE trike with a BBS02 set to 500 watts. That seems to be within the tolerable limits of the DD3 so long as its not abused, and run as a throttle only system - no cadence assist.

I've got a BBS02 sitting in a box that at a later date I'll put to the test with a DD3. I purchased a spare boom as the way the BBS02 mounts its likely to destroy the integrity of the Bottom Bracket internal threads. You would need an extension cable for the Speedo and probably an extension for the throttle. It comes with brake levers that you won't need to connect if you ride throttle only. Depending on where you mount the battery you may need to extend those cables too. Order a few extra power connectors just in case.

On the FS26 I mounted the battery below the boom for the best stability, and to offset the weight of the hubmotor. I'll try this location at first when I mount the BBS02 but it may shift too much weight forward.

I only use power assist on hill climbs thanks to an arthritic knee, and with a 48V 10AH battery my range is about 80 miles riding in the foothills of Tucson.

 

[xrpb11a]

Hi TT..
Thanks for the info.
I plan to run as a throttle only system...just need the boost on short hills and some bursts on flats to get me up to speed.
I was thinking of the BBS02 over the 01 if i need more speed in the future and do away with the DD3/add 3 chainrings on the front...
OTOH, the BBS01 might be a little lighter? Better for keeping the bike "a bike"??

yes...extensions everywhere...was thinking of battery on back rack to distribute the weight better...with short wheelbase all the weight would be in front of front wheel hanging battery from boom.

Do you know if the BBS0* motors add drag when not engaged? I think I read somewhere in these threads that they do.
If so, is it as much as a DD motor disengaged? More or less?

Thanks,
b.

 

[xrpb11a]

Nice writeup on your link...

 

[AnthonyC]

If you don't mind needing the motor on those short steeper climbs 7 gears may be enough, so with a rear wheel IGH motor fitting a triple chainring could be optional. For a lighter build I'm looking at either mid-drive or the rear XD two speed hub motor which has low drag, weighs 7 lbs and should still get up the 1 in 8 hills around here.

As for safety apparently us Streetmachine riders should survive 49mph :-D

http://www.bikeforums.net/recumbent/68054-how-fast-do-you-go-4.html
http://www.bentrideronline.com/messageboard/archive/index.php/t-16466.html

 

[xrpb11a]

Well I got the motor...one heavy sob bss02 500 watts...can't imagine this much weight hanging way out on the boom. Gotta wait 3 weeks for the battery..this should be interesting...